The effect of duration of treatment on therapeutic outcome in group psychotherapy has not been systematically determined. The aim of this study is to compare short-term (30 sessions) and long-term (63 sessions) psychoanalytic group therapy with adult outpatients on multiple measures of outcome. Outpatients referred for group therapy will be randomly assigned to two short- or two long-term groups. Self-report, psychological test, and observer rating data will be collected pre- and post-therapy and at follow-up to assess change. In addition this study employs an act-by-act systematic observation technique (Process Analysis Scoring System) to measure leader and interaction process variables associated with change. The act-by-act scoring is also employed as a means of measuring change through the change in interaction scores during the course of the group sessions themselves. Further data analyses will permit a determination of the relative influence of individual differences, leader, process, and duration of therapy variables on the change process.